Many types of nail coating formulations are available. The majority of such nail coatings are lacquers which consist of a nitrocellulose, aryl sulfonamide formaldehyde resin, plasticizer and organic solvent mixture together with a small proportion of colorant and other ingredients. These nail lacquers have the disadvantages of poor moisture vapor transmission, discoloration of the nail, and require a long drying time. In addition, the nail lacquers contain volatile organic solvents which cause safety, toxicological and environmental concerns.
Film forming compositions have been disclosed in U.S. Pat. Nos. 4,939,233, 4,946,932 and 4,158,053. U.S. Pat. No. 4,939,233 discloses film forming compositions that contain a polyester having repeat units from at least one difunctional sulfomonomer containing at least one metal sulfonate group attached to an aromatic nucleus wherein the functional groups are carboxyl or hydroxyl, and an addition polymer having a majority of repeat units from vinyl acetate, wherein the later polymer is formed from monomers polymerized in an aqueous dispersion of said polyesters. The use of such compositions in nail polishes produce films which exhibit poor adhesion, poor durability and poor water resistance.
U.S. Pat. No. 4,946,932 discloses film forming compositions which contain an aqueous dispersion of a sulfonate group-containing polyester or polyesteramide and a polymer comprising repeat units from one or more .alpha.,.beta.-unsaturated monomers. The use of such compositions in nail polishes produces films which also exhibit poor adhesion, poor durability and poor water resistance.
U.S. Pat. No. 4,158,053 discloses aqueous nail coating formulations which are prepared by an aqueous emulsion polymerization of two or more monomers selected from alkyl acrylates, alkyl methacrylates and styrene compounds. The use of such formulations on nails produce slow drying films which exhibit poor adhesion and poor durability.
U. S. Pat. No. 5,266,322 discloses a nail coating composition prepared from an aqueous emulsion (A) which comprises a sulfopolyester and a copolymer of vinyl acetate and dialkyl maleate, and an aqueous emulsion (B) which comprises an aqueous emulsion of acetoacetoxyethyl methacrylate with a vinyl monomer. The nail coating composition has good adhesive properties and dries fast.
The coloring of nail polishes is discussed in Poucher's Perfumes, cosmetics, and Soaps, 9th ed., Chapman & Hall, N.Y. 1993, p. 252 which states that nail polishes are generally colored with insoluble pigments because water-soluble colorants are known to stain the skin. The difficulty with using insoluble pigments, however, is that the pigment must be exceedingly fine (&lt;300 mesh) in order to remain in suspension during long storage periods. The required small particle size is attained by ball or roll milling which are energy-intensive, costly processes.
U.S. Pat. No. 4,804,719 discloses polymeric compositions which contain carbonyloxy and carbonylamide links, particularly polyesters and polyesteramides, having water solubilizing sulfonate groups and colorants copolymerized onto or into the polymer backbone. It is indicated that these polymers are useful in adhesives, coating materials, films and packaging materials. It is also stated that aqueous dispersions of these materials have utility as inks, paints and other industrial coatings, all of which are intended to be permanent in nature. No disclosure is made relating to the specific art of coloring nails, nonpermanently or otherwise.
Various examples of thermally stable industrial colorants useful for manufacturing colored polymers through incorporation into or onto the sulfopolyester polymer are described in U.S. Pat. Nos. 2,571,319; 3,104,233; 3,034,920; 3,372,138; 3,417,048; 3,489,713; 3,278,486; 3,359,230; 3,401,192; 3,417,048; 3,424,708; 4,049,376; 4,080,355; 4,088,650; 4,116,923; 4,141,881; 4,202,814; 4,231,918; 4,267,306; 4,279,802; 4,292,232; 4,344,767; 4,359,570; 4,403,092; 4,477,635; 4,594,400; 4,617,373; 4,617,374; 4,740,581; 4,745,173; 4,808,677; 4,892,922; 4,892,923; 4,958,043; 4,999,418; 5,030,708; 5,032,670; 5,075,491; 5,086,161; 5,102,980; 5,106,942; 5,151,516; 5,179,207; 5,194,571; 5,274,072; 5,281,658, and 5,384,377. None of the above references suggest the application of such industrial colorants to human nails.
In summary, the water-dispersible colored sulfopolyesters used in this invention have chemical structures different from the colored polymers proposed as nail coatings in the prior art. The combination of water-solubilizing sulfonate groups, colored monomers, and the structure of the sulfopolyester backbone, which may include three to four additional monomers, is unique. Moreover, it is unexpected that such water-dispersible colored sulfopolyesters may be advantageously used for surface coloring of human nails. This result is unexpected due to the important differences in chemical composition and properties between the surface of human nails and the surfaces of cellulose based papers, containers and other man-made substrates onto which inks and paints are normally applied. Adequate wetting adhesion and film formation on the latter surfaces are no predictors of performance on the surface of human nails. In addition, other properties such as removal from the nail with soap and water, resistance to flaking and absence of skin staining could not have been expected from their industrial use as inks, paints or coatings, particularly since such applications are intended to be and are permanent.